Many think that putting topsoil over the seeds would protect it, but in fact, that will actually suffocate the seedlings rather than doing any good. We suggest that straw, hay, or any other type of mulching material be used.
If you're looking for a short answer, then yes, you can put topsoil over grass and existing garden lawns. Although it's possible for grass to grow through the topsoil, this can only be successful depending on the thickness of topsoil applied as a top dressing.
'Never put topsoil over newly planted grass seed,' says Yamaguchi. 'This won't provide healthy growing conditions – it will actually prevent the seedlings from sprouting by essentially suffocating them. ' 'Leaves, straw, and peat moss can be used to help hold moisture for the seed to germinate and grow,' adds James.
(Grass and weeds will grow through soil 2 or 3 inches thick quite easily.) Once you add more than 3 or 4 inches of soil, the amount of weeds and grass that will grow through starts to drop off dramatically. This picture shows the new sod, old lawn, and the soil over top of the old lawn.
Apply Topsoil
Then lay down as much topsoil as you need. For the areas where you want to apply only thin soil, you should use a rake to disperse it evenly. If you leave any solid clumps, it could kill the grass beneath it. As you rake, you'll find that you need to add more, to help fill the holes from aeration.
Compost and Screened Loam with Organics are ideal choices if you're seeding or trying to improve soil conditions. Sand is the ideal choice if you're just trying to smooth out bumpy areas.
A general rule of thumb is that one cubic yard of topsoil will cover an area of 10 feet by 10 feet to a depth of 3 inches.
Most types of grass can grow through 2 inches of topsoil placed on top of it if the existing established plants are healthy. Grass often grows through topsoil when a thinner layer of topsoil is placed on top of an old lawn.
Grass roots grow somewhere between 4 and 6 inches long, so applying a layer of topsoil that is at least 6 inches deep will provide the grass with the room it needs for its roots to grow.
'Gradually add no more than a layer ½in thick, so the grass can grow though it and form roots at a higher level,' continues Steve Bradley. 'If the top dressing is too deep the grass beneath will die off and leave a bare patch where weeds can establish.
Reinvigorate Your Lawn
By spreading grass seed over your existing lawn, you can thicken up the thin areas, and your lawn will start to look terrific again.
To reseed your lawn, fill in bare spots with topsoil before you overseed. This improves the quality of the soil and helps the grass grow. Some bald spots are in areas with water drainage problems. Add a thin layer of sand first and smooth it out with a rake.
Poor soil that is hard and compacted is often the problem when it comes to growing a great lawn. When soil is too alkaline and compacted, air, water and nutrients cannot get down to the roots, and the grass will not grow properly. Lawns thrive in slightly acidic to neutral soil with pH levels between 6.2 and 7.0.
To get a healthy lawn, your soil will ideally be made up of a balance of sand, silt and clay. This is called loam soil. Loam soil holds moisture but also drains well when you water the lawn. It is able to retain nutrients and allow air flow, making it the most ideal soil for plants.
Most grass seed will start growing in about 10-14 days, but sometimes it can take up to 30 days. When you're planting new grass seed in your yard, it can seem like it's taking forever to start sprouting.
The final step of site preparation for planting grass seed is to water the area well. Putting seed down on damp soil encourages speedy germination and provides immediate moisture to emerging roots. Wetting the area before planting is an important step in the process.
It is best to water the grass seedlings 2 to 3 times a day for about 5 to 10 minutes each time. This way you replace any water that has evaporated without oversaturation. It amounts to 3-4 inches of water per week. Once the grass seeds germinate, you should water for a longer period once a day.
Grass needs 10 to 20 cm (4 to 8 inches) of good quality topsoil to grow well. Work the new topsoil into the compacted layer to prevent drainage problems. A rototiller can be very helpful for this.
Topsoil Uses Can Include Fixing Uneven and Patchy Lawns
You may even notice areas of your yard that are slightly uneven. Topsoil is a great remedy for both problems. To grow grass, simply spread topsoil across the area so it is 1 inch deep. Evenly distribute grass seeds and till the soil to combine.
Depending upon your wheelbarrow size (i.e. 2 or 3 cubic feet per wheelbarrow load), it will take 9 to 14 full loads to equal 1 cubic yard. The chart below shows how many full wheelbarrow loads it takes to equal the specified number of cubic yards.
On average, topsoil costs between $12 and $55 per cubic yard or $150 to $600 per truckload. The type of topsoil you choose affects the price of your soil.
Topsoils can vary in screening sizes, therefore some topsoils may be denser than others. Generally speaking, 1 tonne of topsoil will cover 0.63 cubic metres or 22 cubic feet or 0.81 cubic yards. Our bags of topsoil come in sizes of 0.75m³, meaning you'll get just over a tonne of soil per bag!